gmail. I love the fact that if I read an e-mail from my iphone it shows as read if I login online. If i read an e-mail from my computer it automatically shows as read on my iphone. I am also OCD about having un-read messages. I work for AT&T, when a customer comes in with questions about their iPhone and I see that they have 157690 unread e-mails it scares me...lol